Method for preparing bis (fluorosulfonyl) imide organic alkali salt

Abstract

The invention discloses a method for preparing bis (fluorosulfonyl) imide organic alkali salt, which comprises the following steps: (a) adding a solvent into a reactor, and then adding an organic alkali, an inorganic alkaline substance and a phase transfer catalyst; (b) controlling the reaction temperature, simultaneously introducing sulfuryl fluoride and ammonia gas into the reactor, and keeping the temperature after the introduction is finished; (c) filtering to obtain solid fluoride salt and filtrate; and (d) concentrating the filtrate, and washing the obtained concentrate to obtain the bis (fluorosulfonyl) imide organic alkali salt. The method has the advantages that under the action of the phase transfer catalyst, the inorganic alkaline substance can react with the organic alkali hydrofluoride to generate the solid fluoride salt, and meanwhile, the organic alkali is dissociated, so that not only is the selectivity of the reaction ensured, but also the consumption of the organic alkali is greatly reduced, the operation is simple, and industrial implementation is facilitated.

Description

Technical Field

[0001] This invention belongs to the field of chemical synthesis technology and relates to a method for preparing bis(fluorosulfonyl)imide organic base salts. Background Technology

[0002] Lithium bisfluorosulfonylimide (LiFSI) is a white, powdery solid with good thermal stability. It is a key material in lithium-ion battery electrolytes and is considered one of the most likely lithium salts to replace lithium hexafluorophosphate. Its electrolyte conductivity is superior to that of lithium hexafluorophosphate, and it exhibits good compatibility with graphite, silicon anodes, and lithium iron phosphate cathodes. It can improve battery cycle and rate performance, enhance discharge performance at low temperatures, and maintain capacity retention at high temperatures. Lithium bisfluorosulfonylimide is prepared by reacting a bisfluorosulfonylimide organic base salt with a lithium source.

[0003] Difluorosulfonyl imide organic base salts can be prepared by reacting thioyl fluoride and ammonia in the presence of an organic base. For example, Chinese patent CN102378755A discloses a method for preparing difluorosulfonyl imide triethylamine salt. This method uses thioyl fluoride and ammonia as raw materials, acetonitrile as a solvent, and reacts in the presence of triethylamine to obtain a target product with a purity exceeding 99%. Chinese patent CN110217764A discloses a method for preparing difluorosulfonyl imide organic base salts. This method involves reacting ammonia with thioyl fluoride in an organic solvent in the presence of an organic base and a fluoride salt to obtain difluorosulfonyl imide organic base salts. The fluoride salts used are sodium fluoride, potassium fluoride, etc., which effectively avoids the formation of dark-colored impurities, improves the purity of the difluorosulfonyl imide salt, and also increases the reaction rate. Chinese patent CN116283601A uses sulfuryl fluoride and ammonium salt as reactants. Under the action of an aprotic polar solvent and an organic basic acid-binding agent, a reaction is carried out in a high-pressure reactor to obtain the organic ammonium salt of bis(fluorosulfonyl)imide. The ammonium salt used is ammonium fluoride, ammonium chloride, ammonium bromide, etc. Chinese patent CN120329199A uses ammonia, sulfuryl fluoride, and liquid organic base as reactants. Without adding solvent or with a small amount of solvent, the reactants are reacted under pressure to generate the organic base salt of bis(fluorosulfonyl)imide, yielding a product with lower color.

[0004] The methods described above for preparing bis(fluorosulfonyl)imide organic base salts are all carried out in the presence of an organic base. The organic base plays two roles: first, it combines with the bis(fluorosulfonyl)imide generated in the reaction to form the target product, the bis(fluorosulfonyl)imide organic base salt; second, it acts as an acid-binding agent, reacting with the byproduct hydrogen fluoride to form triethylamine hydrofluoric acid. Since the production of 1 mole of bis(fluorosulfonyl)imide generates 2 moles of hydrogen fluoride, to ensure the selectivity of the reaction, the production of 1 mole of the target product, the bis(fluorosulfonyl)imide organic base salt, requires the consumption of 3 moles of organic base. This large consumption of organic base not only increases the cost of raw materials but also increases the cost of subsequent processing and recovery. Therefore, developing a method for preparing bis(fluorosulfonyl)imide organic base salts with low organic base consumption is of paramount importance. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing bisfluorosulfonylimide organic base salts with low organic base consumption.

[0006] The method for preparing bis(fluorosulfonyl)imide organic base salt provided by the present invention includes the following steps: (a) adding a solvent to a reactor, then adding an organic base, an inorganic alkaline substance and a phase transfer catalyst, and lowering the temperature of the material in the reactor to no higher than 10°C; (b) controlling the reaction temperature to no higher than 10°C, and simultaneously introducing sulfuryl fluoride and ammonia into the reactor under stirring, and maintaining the reaction temperature for 0.5 to 3 hours after the gas introduction is completed; (c) filtering to obtain a solid fluoride salt and a filtrate; (d) controlling the temperature to no higher than 50°C, concentrating the filtrate, and washing the concentrate with water to obtain the target product bis(fluorosulfonyl)imide organic base salt.

[0007] According to a preferred embodiment of the present invention, the solvent in step (a) is one or more of toluene, tetrahydrofuran, acetonitrile, and methyl tert-butyl ether, and the organic base is one of trimethylamine, triethylamine, diisopropylethylamine, or tri-n-propylamine, and the weight of the organic base added is 5% to 25% of the weight of the solvent.

[0008] According to a preferred embodiment of the present invention, the inorganic alkaline substance in step (a) is one or more of calcium oxide, lithium carbonate, sodium carbonate, and potassium carbonate, and the molar ratio of the inorganic alkaline substance to the organic base is 1.0 to 3.0:1.

[0009] Optionally, the inorganic alkaline substance described in step (a) can be added to the reactor in a one-time or batch manner.

[0010] According to a preferred embodiment of the present invention, the phase transfer catalyst in step (a) is polyethylene glycol or crown ether, and the weight of the added phase transfer catalyst is 0.01% to 0.5% of the weight of the solvent.

[0011] Furthermore, the polyethylene glycol is one or more of polyethylene glycol-400, polyethylene glycol-600, and polyethylene glycol-800, and the crown ether is one or more of 18-crown ether-6 or 15-crown ether-5.

[0012] According to a preferred embodiment of the present invention, the molar ratio of sulfuryl fluoride and ammonia gas introduced in step (b) is 1.8 to 2.2:1, and the introduction time of sulfuryl fluoride and ammonia gas is 0.5 to 6 hours.

[0013] According to a preferred embodiment of the present invention, the molar ratio of the thioyl fluoride introduced in step (b) to the organic base added in step (a) is 1.0~2.0:1.

[0014] According to a preferred embodiment of the present invention, the temperature in steps (a) and (b) is -15 to 10°C.

[0015] According to a preferred embodiment of the present invention, the filtration in step (c) is one of vacuum filtration, pressure filtration or centrifugal filtration.

[0016] According to a preferred embodiment of the present invention, the concentration in step (d) is carried out by vacuum evaporation concentration, wherein the temperature of the vacuum evaporation concentration is 15~50°C and the vacuum degree is -0.1~-0.08MPa.

[0017] According to a preferred embodiment of the present invention, the water washing temperature in step (d) is 5~20°C, the amount of water used is 0.2~1.0 times the weight of the concentrate, the water washing method is multi-stage cross-flow or counter-flow, and the number of water washings is 1~4 times.

[0018] The advantages of this invention are as follows: In the three-phase reaction system of this invention, sulfuryl fluoride and ammonia generate difluorosulfonylimide organic base salt in the presence of an organic base, and simultaneously produce organic base hydrofluoric acid salt. Under the action of a phase transfer catalyst, inorganic alkaline substances react with organic base hydrofluoric acid salt to generate solid fluoride salt, while simultaneously releasing the organic base, ensuring that the reaction system always maintains the presence of free organic base. This not only guarantees the selectivity of the reaction but also greatly reduces the consumption of organic base. Furthermore, the operation is simple and easy to implement industrially. Solid-liquid separation can be achieved through simple filtration, and the solid fluoride salt can be sold as a byproduct. At the same time, the amount of organic base hydrofluoric acid salt in the concentrate is significantly reduced, lowering the water washing load and water consumption, and greatly simplifying the subsequent wastewater treatment process. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1 (a) Add 200g of acetonitrile to a 500ml reactor, then add 10g (0.17mol) of trimethylamine, 11.2g (0.2mol) of calcium oxide and 1000mg of polyethylene glycol-600, and lower the temperature of the material in the reactor to 10°C; (b) The reaction temperature was controlled at 10°C. Thionyl fluoride and ammonia were simultaneously introduced into the reactor under vigorous stirring. The ratio of thioyl fluoride to ammonia was 1.8:1. The introduction time was 5 hours. The total amount of thioyl fluoride introduced was 30.6 g (0.3 mol). After the gas introduction was completed, the reaction was kept at the temperature for 2 hours. (c) Filter by suction to obtain solid calcium fluoride and filtrate; (d) The temperature was controlled at 40℃ and the vacuum degree was -0.09MPa. The filtrate was evaporated and concentrated. The concentrate was washed three times with 0.4 times the amount of water at 20℃ to obtain the target product, trimethylamine difluorosulfonamide, with a yield of 90.1%.

[0021] Example 2 (a) Add 100g acetonitrile and 100g tetrahydrofuran to a 500ml reactor, then add 30.3g (0.3mol) triethylamine, 22.2g (0.3mol) lithium carbonate and 200mg polyethylene glycol-800, and lower the temperature of the material in the reactor to -5℃; (b) Control the reaction temperature to -5℃, and simultaneously introduce sulfuryl fluoride and ammonia into the reactor under vigorous stirring. The ratio (molar ratio) of sulfuryl fluoride and ammonia is 1.9:1, the introduction time is 5 hours, and the total amount of sulfuryl fluoride introduced is 51g (0.5mol). After the gas introduction is completed, keep the reaction at the temperature for 2 hours. (c) Filter by suction to obtain solid lithium fluoride and filtrate; (d) The filtrate was evaporated and concentrated at a temperature of 40℃ and a vacuum of -0.09MPa. The concentrate was washed three times with 0.3 times the amount of water at 10℃ to obtain the target product, triethylamine difluorosulfonamide, with a yield of 88.7%.

[0022] Example 3 (a) Add 200g of methyl tert-butyl ether to a 500ml reactor, then add 50g (0.35mol) of tri-n-propylamine, 42.4g (0.4mol) of sodium carbonate and 20mg of 15-crown ether-5, and reduce the temperature of the material in the reactor to 5°C; (b) The reaction temperature was controlled at 5°C. Thionyl fluoride and ammonia were simultaneously introduced into the reactor under vigorous stirring. The ratio of thioyl fluoride to ammonia was 2.1:1. The introduction time was 4 hours. The total amount of thioyl fluoride introduced was 61.2 g (0.6 mol). After the gas introduction was completed, the reaction was kept at the temperature for 0.5 hours. (c) Filter by suction to obtain solid sodium fluoride and filtrate; (d) The filtrate was evaporated and concentrated at a temperature of 15℃ and a vacuum of -0.08MPa. The concentrate was washed twice with 0.5 times the amount of water at 10℃ to obtain the target product, tri-n-propylamine difluorosulfonamide, with a yield of 88.0%.

[0023] Example 4 (a) Add 200g of toluene to a 500ml reactor, then add 30.3g (0.3mol) of triethylamine, 13.8g (0.1mol) of potassium carbonate (first batch), and 50mg of 18-crown ether-6, and lower the temperature of the material in the reactor to 5°C; (b) The reaction temperature was controlled at 5°C. Thionyl fluoride and ammonia were simultaneously introduced into the reactor under vigorous stirring. The ratio of thioyl fluoride to ammonia was 2:1. The introduction time was 3 hours. During this period, 13.8g (0.1mol) of potassium carbonate was added at 1 hour and 2 hours respectively. The total amount of potassium carbonate added in the three batches was 41.4g (0.3mol). The total amount of thioyl fluoride introduced was 61.2g (0.6mol). After the gas introduction was completed, the reaction was kept at the temperature for 1 hour. (c) Filter by suction to obtain solid potassium fluoride and filtrate; (d) The filtrate was evaporated and concentrated at a temperature of 40℃ and a vacuum of -0.1MPa. The concentrate was washed twice with 0.3 times the amount of water at 15℃ to obtain the target product, triethylamine difluorosulfonamide, with a yield of 86.8%.

[0024] Example 5 (a) Add 200g tetrahydrofuran to a 500ml reactor, then add 38.7g (0.3mol) diisopropylethylamine, 31.8g (0.3mol) sodium carbonate and 100mg polyethylene glycol-400, and lower the temperature of the material in the reactor to -15°C; (b) Control the reaction temperature at -15℃, and simultaneously introduce sulfuryl fluoride and ammonia into the reactor under vigorous stirring. The ratio (molar ratio) of sulfuryl fluoride and ammonia is 2:1, the introduction time is 6 hours, and the total amount of sulfuryl fluoride introduced is 61.2 g (0.6 mol). After the gas introduction is completed, keep the reaction at the temperature for 3 hours. (c) Centrifuge and filter to obtain solid sodium fluoride and filtrate; (d) The temperature was controlled at 30℃ and the vacuum degree was -0.09MPa. The filtrate was evaporated and concentrated. The concentrate was washed once with 1.0 times the amount of water at 20℃ to obtain the target product, difluorosulfonylimide diisopropyl ethylamine salt, with a yield of 89.3%.

[0025] Comparative Example 1 (a) Add 200g of acetonitrile to a 500ml reactor, then add 10g (0.17mol) of trimethylamine and 11.2g (0.2mol) of calcium oxide, and lower the temperature of the material in the reactor to 10°C; (b) The reaction temperature was controlled at 10°C. Thionyl fluoride and ammonia were simultaneously introduced into the reactor under vigorous stirring. The ratio of thioyl fluoride to ammonia was 1.8:1. The introduction time was 5 hours. The total amount of thioyl fluoride introduced was 30.6 g (0.3 mol). After the gas introduction was completed, the reaction was kept at the temperature for 2 hours. (c) Filter by suction to obtain solid and filtrate; (d) The filtrate was evaporated and concentrated at a temperature of 40℃ and a vacuum of -0.09MPa. The concentrate was washed three times with 0.4 times the amount of water at 20℃ to obtain the target product, trimethylamine difluorosulfonamide, with a yield of 25.6%.

[0026] Comparative Example 2 (a) Add 200g of acetonitrile to a 500ml reactor, then add 10g (0.17mol) of trimethylamine to lower the temperature of the material in the reactor to 10°C; (b) The reaction temperature was controlled at 10°C. Thionyl fluoride and ammonia were simultaneously introduced into the reactor under vigorous stirring. The ratio of thioyl fluoride to ammonia was 1.8:1. The introduction time was 5 hours. The total amount of thioyl fluoride introduced was 30.6 g (0.3 mol). After the gas introduction was completed, the reaction was kept at the temperature for 2 hours. (c) Filter by suction to obtain a small amount of solid and filtrate; (d) The temperature was controlled at 40℃ and the vacuum degree was -0.09MPa. The filtrate was evaporated and concentrated. The concentrate was washed three times with 0.4 times the amount of water at 20℃ to obtain the target product, trimethylamine difluorosulfonamide, with a yield of 21.4%.

[0027] Comparative Example 3 (a) Add 200g of acetonitrile to a 500ml reactor, then add 10g (0.17mol) of trimethylamine, 8.0g (0.2mol) of sodium hydroxide and 1000mg of polyethylene glycol-600, and reduce the temperature of the material in the reactor to 10°C; (b) The reaction temperature was controlled at 10°C. Thionyl fluoride and ammonia were simultaneously introduced into the reactor under vigorous stirring. The ratio of thioyl fluoride to ammonia was 1.8:1. The introduction time was 5 hours. The total amount of thioyl fluoride introduced was 30.6 g (0.3 mol). After the gas introduction was completed, the reaction was kept at the temperature for 2 hours. (c) Filter by suction to obtain solid and filtrate; (d) The temperature was controlled at 40℃ and the vacuum degree was -0.09MPa. The filtrate was evaporated and concentrated. The concentrate was washed with 0.4 times the amount of water at 20℃. The concentrate was completely dissolved in water, and the target product, difluorosulfonylimide trimethylamine salt, was not obtained.

[0028] As can be seen from the above comparative examples, the yield of the target product is significantly reduced when no phase transfer catalyst or inorganic alkaline substance is used; the target product cannot be obtained when sodium hydroxide is used as the inorganic alkaline substance.

[0029] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A method for preparing bis(fluorosulfonyl)imide organic base salt, characterized in that, Includes the following steps: (a) Add solvent to the reactor, then add organic base, inorganic alkaline substance and phase transfer catalyst, and lower the temperature of the material in the reactor to no higher than 10°C; (b) Control the reaction temperature to no higher than 10°C, and simultaneously introduce sulfuryl fluoride and ammonia into the reactor under stirring. After the gas introduction is completed, keep the reaction at the temperature for 0.5 to 3 hours; (c) Filter to obtain solid fluoride salt and filtrate; (d) Control the temperature to no higher than 50°C, concentrate the filtrate, and wash the concentrate with water to obtain the target product difluorosulfonylimide organic base salt.

2. The method for preparing bis(fluorosulfonyl)imide organic base salt according to claim 1, characterized in that, The solvent in step (a) is one or more of toluene, tetrahydrofuran, acetonitrile, and methyl tert-butyl ether, and the organic base is one of trimethylamine, triethylamine, diisopropylethylamine, or tri-n-propylamine. The weight of the organic base added is 5% to 25% of the weight of the solvent.

3. The method for preparing bis(fluorosulfonyl)imide organic base salt according to claim 1, characterized in that, The inorganic alkaline substance mentioned in step (a) is one or more of calcium oxide, lithium carbonate, sodium carbonate, and potassium carbonate, and the molar ratio of the inorganic alkaline substance to the organic base is 1.0~3.0:1; the inorganic alkaline substance is added to the reactor in a one-time or batch manner.

4. The method for preparing bis(fluorosulfonyl)imide organic base salt according to claim 1, characterized in that, The phase transfer catalyst mentioned in step (a) is polyethylene glycol or crown ether, and the weight of the added phase transfer catalyst is 0.01% to 0.5% of the weight of the solvent.

5. The method for preparing bis(fluorosulfonyl)imide organic base salt according to claim 4, characterized in that, The polyethylene glycol is one or more of polyethylene glycol-400, polyethylene glycol-600, and polyethylene glycol-800, and the crown ether is one or more of 18-crown ether-6 or 15-crown ether-5.

6. The method for preparing bis(fluorosulfonyl)imide organic base salt according to claim 1, characterized in that, The molar ratio of sulfuryl fluoride and ammonia gas introduced in step (b) is 1.8~2.2:1, and the introduction time of sulfuryl fluoride and ammonia gas is 0.5~6 hours; the molar ratio of sulfuryl fluoride introduced in step (b) to organic base added in step (a) is 1.0~2.0:

1.

7. The method for preparing bis(fluorosulfonyl)imide organic base salt according to claim 1, characterized in that, The temperature in steps (a) and (b) is -15 to 10°C.

8. The method for preparing bis(fluorosulfonyl)imide organic base salt according to claim 1, characterized in that, The filtration described in step (c) is one of vacuum filtration, pressure filtration or centrifugal filtration.

9. The method for preparing bis(fluorosulfonyl)imide organic base salt according to claim 1, characterized in that, The concentration in step (d) is carried out by vacuum evaporation concentration. The temperature of vacuum evaporation concentration is 15~50℃ and the vacuum degree is -0.1 ~ -0.08MPa.

10. The method for preparing bis(fluorosulfonyl)imide organic base salt according to claim 1, characterized in that, The water washing temperature in step (d) is 5~20℃, the amount of water used is 0.2~1.0 times the weight of the concentrate, the water washing method is multi-stage cross-flow or counter-flow, and the number of water washings is 1~4 times.